Brown-throated three-toed sloth
Bradypus variegatus

B. variegatus ranges from Honduras in the north, through southern Central America. In South America, it ranges from Colombia into western and southern Venezuela, and south into Ecuador, eastern Peru and Bolivia, into Brazil and northern Argentina (where it is probably extinct). Its distribution overlaps with B. torquatus in the central part of the Atlantic forest. In Brazil, the species currently occurs in forested areas of the Amazon, Atlantic forest, and Cerrado biomes. There are historical records of B. variegatus in the Caatinga biome. Its presence in the Pantanal biome of Brazil remains unconfirmed, but the species might occur in the contact zones between this biome and the Amazon forest to the north. Additional field studies are thus necessary in order to properly define the current species distribution in the Cerrado, Caatinga and Pantanal. The southernmost distribution of this sloth in Brazil was reported by Cabrera (1957) as the state of Rio Grande do Sul, which could, however, not be confirmed (Gardner, 2007). It is historically absent from the state of Santa Catarina (Brazil) and northeastern Argentina; the southernmost confirmed record of the species is near Londrina, in the state of Paraná, Brazil, but today it is considered extinct in this state (Mikich and Bernils, 2004). The last record from Argentina dates back to 1916 (Vizcaíno et al., 2006), but field studies specifically aiming at this species are lacking from this country. B. variegatus is found from sea level to at least 2,400 m asl (Ureña et al., 1986).


This gregarious, arboreal mammal has a predominantly gray fur. The hair on abdomen and chest is short and marbled, while the back bears longer, thicker, gray to brownish hair with whitish spots. The color of the throat may vary individually from gray to brownish. This three-toed sloth has a small, round head with small ears that are hidden under the fur. The face is white, with some black around the eyes. The forelimbs bear three digits with large claws and are longer than the hindlegs, which also have three digits. The tail is very short and stumplike. Adult males have a black and orange spot (called speculum) between the shoulder blades.


The brown-throated three-toed sloth has been recorded from a number of forest types including seasonal mesic tropical forest, semi-deciduous forest (inland Atlantic forest), cloud forest, and lowland tropical forest. It inhabits cacao plantations in Costa Rica (Vaughan et al., 2007).


This sloth species produces one litter of one infant at intervals of at least 19 months (Bezerra et al., 2008; T. Plese, pers. comm., 2010). Mating period varies depending on the year and geographical region, but occurs mainly in spring (i.e., from July to November in South America and from February to May in Central America).
Population densities of B. variegatus have been estimated at 2.2 to 6.7 animals per hectare in the Brazilian Amazon (Queiroz, 1995), 8.5 animals per hectare in Panama (Montgomery and Sunquist, 1975), and 0.6 to 4.5 animals per hectare in the tropical dry forest of Colombia (Acevedo and Sanchez, 2007). No demographic information is available from the remaining area of distribution. B. variegatus is commonly found in public squares, where densities can reach 12.5 animals per hectare (Manchester and Jorge, 2009). Severe fragmentation has been reported from the populations in Colombia and from the eastern Brazilian subspecies B. v. brasiliensis, which presents the lowest levels of genetic diversity among all B. variegatus. The genetic diversity is only comparable to that observed in the critically endangered pygmy sloth (B. pygmaeus). Molecular studies also indicate that genetic diversity in the northern Atlantic forest subspecies B. v. variegatus is lower than values observed for sympatric populations of B. torquatus (Moraes-Barros et al., 2006).


It appears that there are no major threats to B. variegatus at the global level. Nevertheless, some populations, especially in Colombia and Brazil, are declining due to deforestation leading to severe habitat degradation and fragmentation. Furthermore, they are hunted by local indigenous communities. In Brazil, especially in the northeastern region and in the Amazon, and in Colombia the common sloth is hunted and sold in public markets as food, medicine, and as a pet species. In several touristic sites, B. variegatus is used by locals to entertain visitors. Wild-caught individuals, especially offspring, are sold as pets to tourists in Colombia (Moreno and Plese, 2006). This illegal trade is increasing and represents a cause of concern due to its impact on the wild populations.


The brown-throated three-toed sloth is listed as Least Concern in view of its wide distribution including a large part of the Amazon forest, presumed large population, its occurrence in a number of protected areas, and because it is unlikely to be declining fast enough to qualify for listing in a threatened category. This species is present in many protected areas. It is included in CITES Appendix II. Education and awareness programs are being carried out by Fundación AIUNAU in Colombia.


Additional information and a complete list of references can be found in: Superina, M., T. Plese, N. Moraes-Barros and A.M. Abba (2010): The 2010 Sloth Red List Assessment. Edentata 11(2): 115-134. This article is available here.

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